QB bottom wing skin alignment

[jdeas]

Guys,
Tonight I decided to 'store' the bottom skins by clecoing them to the wings at the end of the night. What I got worries me somewhat.
As was to be expected, I had to warp the ribs somewhat to lineup the holes and insert Clecos every 4 or 5 locations but what I didn't expect was the hole offset at the spar!

After aligning the ribs and attaching to the rear spar I had a significant offset for the #40 holes in the main spar.

The darker shadow in the holes above are the edges of the countersink in the spar.

The flash and backlight show this as well

The flash picture is not making it look worse! The offset is bad enough where even with the cleco a few inches away there is an offset on the spar.
This offset appears constant and not some sort of warp inboard to outboard. Looking at the inboard skins that were already assembled, the gap between skins (.01~.02) is also much less that what I can do with the outboard skins(.04~.06).

I really can't think of a good way to approach this. The spars are drilled and the main is also countersunk. How could I drill and dimple a skin this far off?

 

[Harvey L. Sorensen]

bottom skin

This may not work but remove all clecos and start with the main spar and work to the rear putting in clecos as you progress rearward. This might work.

 

[rickmellor]

I had similar alignment issues with the first fitting. Like Harvey says, try working from a different direction and things should get pulled into better alignment. I worked inboard->outboard, clecoing the main & rear spars and the rib as I went, and everything came out ok. My suspicion is that since we're not using a jig to hold the wings true, there's enough play in there to cause this kind of problem. The wing is not completely rigid until that bottom skin is in place.

-Rick

 

[jdeas]

This may not work but remove all clecos and start with the main spar and work to the rear putting in clecos as you progress rearward. This might work.

I tried that as well. Doing that I can (for the most part) get all the clecos into the front and rear spar but then all the ribs are offset (rib higher that skin) by 20%-30%. The Clecos would bend the skin in any attempt to aligh the skin to ribs.
Do most people place the wing flat while working on this section (for flex reasons)?

 

[rickmellor]

FWIW, mine were flat on the bench.

-Rick

 

[Larco]

I will suggest calling Vans. I have completed 5 sets of QB wings and not seen this before, the skin has always fit very nice. Could the CNC punch machine have been set up wrong???? Once in awhile a mistake has shown up and I'm sure they will help out. Larry

 

[apatti]

I tried that as well. Doing that I can (for the most part) get all the clecos into the front and rear spar but then all the ribs are offset (rib higher that skin) by 20%-30%. The Clecos would bend the skin in any attempt to aligh the skin to ribs.
Do most people place the wing flat while working on this section (for flex reasons)?

My slow-build wings were flat on the table when I clecoed the bottom wings for storage. I seem to recall a similar issue with alignment.

From what you said above it sounds like you clecoed the main spar and then jumped to the rear spar. I would recommend the following:
- begin clecoing in the middle of the main spar
- insert clecos along the main spar inboard and outboard for about 2.5 - 3.5 bays
- cleco down the center-most rib to just before the rear spar
- cleco down one rib inboard of the center-most rib to just before the main spar
- cleco down one rib outboard of the center-most rib to just before the main spar
- cleco down the next inboard/outboard rib about half-way to the rear spar
- cleco along the main spar inboard and outboard the rest of the way
- finish clecoing down the ribs
- starting in the center of the rear spar, cleco inboard/outboard along the rear spar

In general, think like you are making a bed. You want to smooth out the wrinkles from the center out and from the top (main spar) down (rear spar). You might want to put clecos in about every other hole at first. As an area (bay) gets fully clecoed and aligned you can then go back and begin removing some of the clecos.

Good luck and let us know what ends up working.

 

[Jekyll]

The dimples help to really pull everything together into place.

Jekyll

 

[jdeas]

I will try the center out method tomorrow and maybe a call to Vans.
Thanks for the input guys,
JD

 

[jdeas]

The dimples help to really pull everything together into place.

Jekyll

I know the dimples will help but at this point I'm just trying to make sure the structure can be match drilled. Have people skipped match drilling and just used the prepared and dimpled skin to force an alignment? Up to now I have done my best to make sure there is no tension on the clecos before match drilling as that tends to elongate the holes.

 

[T.S.]

lower skins

I just went through this and found the same. I ended up clecoing starting from the main spar and woking to the rear spar. The rear spar has some flex to get the clecos in and all fit better. Also, it helped to square up the flanges of the ribs in place and touch up the fluting done by the QB crew which was WAY off.

T.S.
7A

 

[jdeas]

I just went through this and found the same. I ended up clecoing starting from the main spar and woking to the rear spar. The rear spar has some flex to get the clecos in and all fit better. Also, it helped to square up the flanges of the ribs in place and touch up the fluting done by the QB crew which was WAY off.

T.S.
7A

I agree with the assesment that the ribs needs some work. I also found that the rear spar will flex a bit. When I do this though I still have a 'front to back' misalignment where the rib holes are too far aft to match the skin. I don't know how I could change the bend where the rib meets the forward spar. I suppose it's possible that the forward flange needs alteration but how would that been done once already attached?